Before describing such systems in greater detail, it is important to recall what known electronic memory cards consist of. The card comprises a body of plastic material having an electronic module implanted therein, the module comprising a semiconductor chip having an integrated circuit formed thereon together with contact tabs which are disposed on one of the main faces of the card body and which are electrically connected to the terminals of the integrated circuit. The card must have standardized dimensions, and in particular its thickness must be less than one millimeter and the contact tabs must be in specified positions relative to the edges of the card. In addition, the card together with its electronic module must satisfy mechanical tests, and in particular bending tests, in order to ensure that the electronic module will not come unstuck from the body of the card. Given the thinness of the card body, numerous problems are encountered in implanting the electronic module in the body. In particular, the hollows required for receiving the electronic module must be provided with precision, in particular relating to the location of the hollow relative to the outside edges of the card body. In addition, implanting an electronic module in a card body requires a certain number of operations to be performed which must be repeated when manufacturing each card.
It will be understood that the cost of manufacturing a card body and fixing an electronic module in the card body is by no means negligible. In contrast, for a given architecture, the cost of manufacturing an integrated circuit tends to fall off significantly. Consequently, in the overall manufacturing cost of an electronic memory card, the fraction due to manufacturing the body of the card and to implanting the electronic module tends to increase considerably. As a result, within a given organization the solution which consists in providing one card for each function considerably increases the fixed cost which is specifically related to manufacturing the cards. The smaller the amount of money's worth stored in the card, the less the user is prepared to accept this fixed cost.
It is also disagreeable for a user to have to keep on the person a plurality of different cards for obtaining different commonly used services.
The other solution which consists in providing a single card for giving access to different services requires an integrated circuit of much more complicated architecture in order to enable a single circuit to provide different functions. This implies an integrated circuit including wired logic structure or microprocessor structure together with large memory capacity. As a result, the integrated circuit will be considerably more expensive and the area of the semiconductor chip will be considerably larger. The first point means that the number of different functions must be very small, and the second point naturally makes implanting the electronic module in the card more difficult.
Further, if the number of available services increases, or if access to data handling networks needs to be better protected, the authorization or authentification procedures of the card and/or the card-bearer must be reinforced without inconveniencing the user, i.e. without making the operations which the user must perform to gain access to services or to a data network more complex.
An aim of the invention is to provide a data processing system for smart cards having a plurality of electronic modules and avoiding the above-mentioned drawbacks.
Before describing the invention, it is appropriate to specify what is meant in the present text by the term "card processing device".
"Card processing device" means a device into which a smart card (i.e. one including electronic memory) may be inserted and which is capable of reading the data stored in the card, of writing new data into the card and also of processing the data read together with data coming from elsewhere in order to authorize access to a service or to a data network. As is well known, another function of the processing device is to provide the integrated circuit of the card with its electrical power supply since cards do not, in general, include their own power supply.